A wellbore is often drilled into a subterranean formation for recovering hydrocarbons, storing hydrocarbons, or injecting other fluids, such as carbon dioxide or aqueous fluids, for storage or disposal, or for recovery of deposited minerals or geothermal energy.
Typically the wellbore is lined with a steel casing through which fluid is conveyed under pressure. The steel casing is cemented in the wellbore in order to provide zonal isolation so that the fluid is extracted from or delivered to selected zones or layers of the formation and prevented from leaking into other zones or layers of the formation and leaking into the surface environment. The cement also bonds to and supports the casing.
For a well drilled into a rock formation, the wellbore is typically drilled into the rock, and then the casing is placed into the wellbore in the rock. A cement slurry is then pumped down through the casing, and the cement slurry flows out the bottom of the casing and rises up into the annulus around the casing in the wellbore. As the cement slurry is pumped, the pressure and flow rate are recorded in order to detect abnormalities. Tags, such as sensors, can be placed in the cement within the wellbore, to assist in obtaining or generating information about components within the wellbore.